- For the cupcakes
- 75g plain flour
- 200g caster sugar
- 75g butter
- 1 ½tsp baking powder
- 2 eggs, at room temperature
- 90ml whole milk, at room temperature
- 1tsp vanilla bean paste
- 60g digestive biscuits
- Ganache filling
- 100g dark chocolate (70–80% cocoa solids)
- 1 tsp butter
- 50ml double cream
- Marshmallow topping
- 125g caster sugar
- 75g golden syrup
- 2 large egg whites
- ½ tsp vanilla extract
- 4 squares of dark chocolate, to decorate
To make the cupcakes, preheat the oven to 180C/gas 4. Line the cupcake tin with 12 cupcake cases.
Blitz the digestive biscuits in a food processor until they are finely ground, or put them into a sealable bag, seal the bag and crush with a rolling pin. In the bowl of a stand mixer, combine the flour, crushed biscuits, sugar, butter and baking powder using the paddle attachment. Mix on a low speed until the mixture resembles fine breadcrumbs. Mix on a low speed until the mixture resembles fine breadcrumbs. You shouldn’t see any large lumps of butter. Alternatively, use your fingers to rub the butter into the flour and sugar.
In a small jug, use a fork to blend the eggs, milk and vanilla bean paste together. Add the mixture a little at a time to the bowl, beating until it is all combined. Keep beating for a few minutes more, until the mixture is uniform and smooth with no lumps.
Divide the mixture between the cases evenly, filling each one no more than two-thirds full. Bake in the preheated oven for 16-18 minutes, until a skewer inserted comes out clean and the cakes are a pale golden brown. Don’t be tempted to over-bake here; get them out as soon as the skewer is clean. The last thing you want is dry cakes.
Leave to cool for five minutes in the tin, then remove and leave to cool completely on a cooling rack. Do not attempt to core, fill or decorate them until they are cold.
To make the filling, finely chop the chocolate and put it into a small bowl. Heat the butter and cream in a saucepan until steaming hot but not boiling, then pour over the chocolate. Remove from the heat and leave to stand for a minute before stirring to form a smooth ganache. If any lumps of chocolate remain, put the bowl into the microwave for ten seconds then stir; repeat until the lumps are gone. Chill in the fridge for 30 minutes or so, until it is firm and scoopable.
To make the marshmallow topping, put the sugar, golden syrup and 2 tablespoons of water into a saucepan and cook over a medium-high heat without stirring until the mixture reaches the soft-ball stage (118°C on a sugar thermometer). If you don’t have a thermometer, the mixture is ready when the bubbles start to stick together in the pan and it drips off a spoon in a steady stream. Remove from the heat.
Put the egg whites into a clean, grease-free bowl and whisk with an electric hand-held whisk until soft peaks form. With the whisk on low, carefully pour the hot sugar onto the egg whites, whisking all the time. When all the sugar has been added, increase the speed to high and whip until the sides of the bowl feel only slightly warm and the mixture is thick and glossy. Add the vanilla extract at the end. This icing is easiest to pipe when it is warm, so transfer immediately to a piping bag fitted with a large circular nozzle or with the tip cut off.
To assemble, use a sharp knife or specialist cupcake corer to make a circular incision in the centre of each cupcake, remove the centre and fill each one with a teaspoon of the chocolate filling.
Pipe a large mound of marshmallow topping on the top of each cupcake, covering the chocolate filling. Use a blowtorch, if you have one, to lightly brown each one, avoiding the paper case as this will burn. You could use the grill to brown the marshmallow topping, but watch carefully because it is more difficult to control the colour and prevent it burning.
To finish, chop the chocolate squares finely and sprinkle over the top of the marshmallows.